Speakers come in all shapes and sizes, enabling you to listen to music on your portable media player, enjoy a film at the cinema, or hear a friend’s voice over the phone. But how do they work?
In order to convert an electrical signal into sound, a speaker contains an electromagnet which is a metal coil that creates a magnetic field when an electric current flows through it. This coil behaves much like a normal magnet with one unique property: reversing the direction of the current in the coil flips the poles of the magnet.
Inside a speaker, an electromagnet is placed in front of a permanent magnet and is fixed firmly into position while the electromagnet is not. As pulses of electricity pass through the coil of the electromagnet, the direction of its magnetic field is rapidly changed. This in turn attracts and then repels the permanent magnet, vibrating back and forth. .
The electromagnet is usually attached to a cone made of a flexible material such as paper or plastic which amplifies these vibrations, pumping sound waves into the surrounding air and towards your ears.